1. Field of the Invention
The present invention relates to a buckle device that configures a seat belt device in a vehicle and is for retaining a tongue plate attached to a webbing.
2. Description of the Related Art
There is a buckle device that includes a buckle body configuring a frame, a lock plate movable toward and away from a tongue plate inserted into the buckle body, and a release button attached, such that it is movable within a predetermined range, to the buckle body (e.g., see Japanese Patent Application Publication (JP-A) No. 5-278564).
In the buckle device disclosed in JP-A No. 5-278564, when the tongue plate is inserted into the buckle body (buckle base), the lock plate (latch) approaches and engages with the tongue plate, whereby the tongue plate is retained in the buckle body. When the release button (press button) is push-operated, the lock plate separates from the tongue plate and the retention is released.
In the buckle device with this configuration, the release button includes an operation portion that is push-operated by a passenger and a pair of arm portions that extend along the operation direction from both width-direction ends of the operation portion. Guide protrusions that protrude in directions in which they face each other are formed on the ends of the pair of arm portions. The guide protrusions movably fit into elongated holes formed in side walls of the buckle body, whereby the release button is attached to the buckle body.
However, in the buckle device with this configuration, there is the problem that assemblability is poor because when the release button is to be assembled with respect to the buckle body, the guide protrusions cannot be fitted into the elongated holes in the buckle base unless the pair of arm portions are greatly bent in the directions in which they separate from each other.
Also, in the buckle device with this configuration, when the push load is biasingly applied to one width-direction end (one arm portion) of the operation portion when the operation portion of the release button is push-operated, the one arm portion and the other arm portion are alternately displaced along the operation direction, and strain arises in the release button. If the strain in the release button is large, sometimes a sufficient operation stroke of the release button cannot be secured and the retention of the tongue plate cannot be reliably released. For this reason, in the buckle device with this configuration, it is necessary to preset the operation stroke of the release button to be long, which results in the size of the device becoming large.